Semiconductor device and method for manufacturing the same

ABSTRACT

It is made possible to provide a semiconductor device and a method for manufacturing the semiconductor device that have the highest possible permittivity and can be produced at low production costs. A method for manufacturing a semiconductor device, includes: forming an amorphous film containing (Hf z Zr 1−z ) x Si 1−x O 2−y  (0.81≦x≦0.99, 0.04≦y≦0.25, 0≦z≦1) on a semiconductor substrate, the ranges of composition ratios x, y, and z being values measured by XPS; and transforming the amorphous film into an insulating film containing (Hf z Zr 1−z ) x Si 1−x O 2  as tetragonal crystals, by performing annealing at 750° C. or higher on the amorphous film in an atmosphere containing oxygen.

CROSS-REFERENCE TO RELATED APPLICATION

This application is based upon and claims the benefit of priority fromprior Japanese Patent Application No. 2006-125735 filed on Apr. 28, 2006in Japan, the entire contents of which are incorporated herein byreference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a semiconductor device and a method formanufacturing the semiconductor device.

2. Related Art

The insulating films in semiconductor devices have become thinner by theimproved semiconductor techniques for producing smaller devices. Insemiconductor production, SiO₂ is an excellent insulating material, andhas been used over a long period of time. In a gate insulating film,however, the film thickness of a SiO₂ film has become as small as thesize equivalent to a few atomic layers. As a result, it has becomedifficult in principle to restrain current leakage through such a thininsulating film. Instead of SiO₂, a material having higher permittivitycan be used as an insulating film, and the material can electricallyserve as if it were a thin SiO₂ film. Even if such a film is thickerthan the few atomic layers in the case of a SiO₂ film, the film iselectrically equivalent to the SiO₂ film. Accordingly, it is assumedthat current leakage can be restrained with such a film.

In a flash memory or the like, there is an interelectrode insulatingfilm that isolates the control gate from the floating gate. However,such an interelectrode insulating film is also expected to have higherpermittivity, as the device size has become smaller.

In this trend, high-permittivity insulating films (high-k films) havebeen studied, and as of today, gate insulating films containing hafniumare considered to have the greatest potential. However, the permittivityof a gate insulating film containing hafnium is approximately 25 at amaximum. In practice, the composition ratio of hafnium is highly likelyto be lower than that. Therefore, such a gate insulating film containinghafnium as a high-k film can achieve relative permittivity as low as 12.

If a tetragonal crystalline structure can be formed from zirconia(zirconium oxide) or hafnia (hafnium oxide) through the first principlecalculation, higher relative permittivity might be achieved. Thispossibility is suggested in by G. M. Ringanese, X. Gonze, G. Jun, K.Cho, and A. Pasquarello in Phys. Rev. B69, 184301 (2004) (hereinafterreferred to as Reference 1), for example. To confirm the possibilitythrough experiments, they have tried to form tetragonal crystallinestructures by adding yttrium to zirconia or hafnia (disclosed by H.Kita, K. Kyuno, and A. Toriumi, in Appl. Phys. Lett. 86, 102906 (2005))(hereinafter referred to as Reference 2).

Further, increases in permittivity by adding silicon to hafnia aredisclosed by I. Tomida, H. Kita, K. Kyuno, and A. Toriumi in Appl. Phys.Spring Lectures, 25P-V-3, 2006 (hereinafter referred to as Reference 3).

By the technique disclosed in Reference 2, however, a tetragonalcrystalline structure has not successfully been produced to provide thehighest relative permittivity, as can be seen from the X-ray diffractionprofiles.

In Reference 2, they tried to increase the permittivity by usingrare-earth elements or alkaline-earth elements that were rarely used insemiconductor processes. Since those elements are soluble with zirconiaand hafnia, it was considered that the permittivity could be easilyincreased with those materials. However, in the real semiconductormanufacturing processes that thoroughly refuse contamination, it is noteasy to predict all the side effects and adverse influence that might becaused by the introduction of a rare-earth element or an alkaline-earthelement. Therefore, the costs for introducing rare-earth elements oralkaline-earth elements are predicted to be very high.

If the dielectric disclosed in Reference 3 is used as a gate insulatingfilm in real LSI production, as described later, the mobility might bereduced due to the stress exerted on the channel region in directcontact with the gate insulating film, or lattice relaxation to reducethe relative permittivity to the original value might be caused in thegate insulating film, or the gate insulating film might break itselfbecause of the stress. As a result, the device characteristics might bedegraded.

SUMMARY OF THE INVENTION

The present invention has been made in view of these circumstances, andan object thereof is to provide a semiconductor device and a method formanufacturing the semiconductor device that have the highest possiblepermittivity and can be produced at low production costs.

A method for manufacturing a semiconductor device according to a firstaspect of the present invention includes:

forming an amorphous film containing (Hf_(z)Zr_(1−z))_(x)Si_(1−x)O_(2−y)(0.81 ≦x≦0.99, 0.04≦y≦0.25, 0≦z≦1) on a semiconductor substrate, theranges of composition ratios x, y, and z being values measured by XPS;and transforming the amorphous film into an insulating film containing(Hf_(z)Zr_(1−z))_(x)Si_(1−x)O₂ as tetragonal crystals, by performingannealing at 750° C. or higher on the amorphous film in an atmospherecontaining oxygen.

A method for manufacturing a semiconductor device according to a secondaspect of the present invention includes: forming an amorphous filmcontaining (Hf_(z)Zr_(1−z))_(x)Si_(1−x)O_(2−y) (0.76≦x≦0.985,0.04≦y≦0.25, 0≦z≦1) on a semiconductor substrate, the ranges ofcomposition ratios x and z being values measured by RBS, the range of acomposition ratio y being values measured by XPS; and transforming theamorphous film into an insulating film containing(Hf_(z)Zr_(1−z))_(x)Si_(1−x)O₂ as tetragonal crystals, by performingannealing at 750° C. or higher on the amorphous film in an atmospherecontaining oxygen.

A semiconductor device according to a third aspect of the presentinvention includes: an insulating film containing(Hf_(z)Zr_(1−z))_(x)Si_(1−x)O₂ (0.81≦x≦0.99, 0≦z≦1) formed on asemiconductor substrate, the ranges of composition ratios x and z beingvalues measured by XPS, the insulating film having a main phase that isa tetragonal fluorite-type crystalline structure, molecular volume V_(m)of tetragonal crystals in the insulating film being in the range of0.03353 nm³≦V_(m)≦0.03424 nm³ per (Hf_(z)Zr_(1−z))_(x)Si_(1−x)O₂, theinsulating film having a physical film thickness of 110 nm or smaller.

A semiconductor device according to a fourth aspect of the presentinvention includes: an insulating film containing(Hf_(z)Zr_(1−z))_(x)Si_(1−x)O₂ (0.76≦x≦0.985, 0≦z≦1) formed on asemiconductor substrate, the ranges of composition ratios x and z beingvalues measured by RBS, the insulating film having a main phase that isa tetragonal fluorite-type crystalline structure, molecular volume V_(m)of tetragonal crystals in the insulating film being in the range of0.03353 nm³≦V_(m)≦0.03424 nm³ per (Hf_(z)Zr_(1−z))_(x)Si_(1−x)O₂, theinsulating film having a physical film thickness of 110 nm or smaller.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a flowchart showing the procedures by a method formanufacturing a semiconductor device in accordance with each embodiment;

FIG. 2 shows an X-ray diffraction profile indicating a tetragonalcrystalline state in an insulating film produced by a manufacturingmethod in accordance with a first embodiment;

FIG. 3 shows X-ray diffraction peak intensities calculated with respectto a variety of zirconia crystalline structures;

FIG. 4 is a temperature-pressure phase diagram about zirconia;

FIG. 5 shows an X-ray diffraction profile indicating a tetragonalcrystalline state in an insulating film produced by a manufacturingmethod in accordance with a second embodiment;

FIG. 6 is a temperature-pressure phase diagram about hafnia;

FIG. 7 shows the existence of a Zr-Si bond by XPS in an insulating filmthat has an oxygen defect and is produced by a manufacturing method inaccordance with a fourth embodiment;

FIG. 8 shows X-ray diffraction profiles indicating that tetragonalcrystals are obtained in thin insulating films of 10 nm or 5 nm in filmthickness produced by a manufacturing method in accordance with thefourth embodiment;

FIG. 9 shows the relative permittivity observed by examining theelectric properties of insulating films produced by the manufacturingmethod in accordance with the fourth embodiment;

FIG. 10 is a phase diagram of HfO₂ and ZrO₂ at all ratios;

FIG. 11 is a cross-sectional view of a CMOS device as a specific exampleof a sixth embodiment;

FIG. 12 is a cross-sectional view of a memory cell of a floating gatetype flash memory as a second specific example of the sixth embodiment;

FIG. 13 shows the pressure dependence of the unit call volume of hafniacrystals;

FIG. 14 shows the X-ray diffraction profiles of insulating films ofZr_(x)Si_(1−x)O₂ where the composition ratio x of Zr is 0.86, 0.90,0.94, 0.98, and 1.00 in XPS measurement; and

FIG. 15 is a cross-sectional view of a memory cell of a MONOS type flashmemory.

DETAILED DESCRIPTION OF THE INVENTION

The following is a description of embodiments of the present invention,with reference to the accompanying drawings.

In each of the embodiments of the present invention, Si, which isgenerally considered not soluble, is added to zirconia or hafnia, so asto increase the permittivity. In XPS (X-ray Photoelectron Spectroscopy)measurement, 6 atomic % to 14 atomic % of Si is added, and in RBS(Rutherford Back-scattering Spectrometry) measurement, 8 atomic % to 19atomic % of Si is added, so as to form a thin film having tetragonalcrystals with a lattice constant approximately 1% smaller than that ofconventional tetragonal crystals. This thin film has a crystallinestructure in which the moving range of oxygen ions in the tetragonalcrystals is wider. As the polarizability is approximately 8% higher, apermittivity of 20 to 26 that is higher than 17, which is the relativepermittivity of zirconia and hafnia, can be achieved.

In the following embodiments, in the XPS measurement, the relativesensitivity coefficient of a Si2p peak is 0.37, the relative sensitivitycoefficient of Zr3d is 2.40, and the relative sensitivity coefficient ofHf4f is 2.56. In the RBS measurement, He⁺ ions are used with anacceleration voltage of 2.275 MeV, a scattering angle of 160 degrees,and a dose amount of 40 μc.

First Embodiment

A method for manufacturing a semiconductor device in accordance with afirst embodiment of the present invention is described.

First, as shown in step S1 of FIG. 1, an amorphous insulating film thathad a composition of Zr_(0.86)Si_(0.14)O_(1.75) in the XPS measurementwith a smaller amount of oxygen than the oxygen stoichiometry was formedon a single-crystal silicon substrate that had a natural oxide filmremoved with a diluted hydrofluoric acid. The amorphous insulating filmwas formed by a sputtering technique, and the film formation was carriedout in a mixed atmosphere of argon and oxygen, with Zr and Si being thetargets. The amount of oxygen loss is the value obtained on the basis ofthe ratio of the peak intensity of a Zr-O bond of Zr3d measured by XPSto the peak intensity of a Zr-Zr or Zr-Si bond measured by XPS, on theassumption that the peaks of Zr-Zr and Zr-Si bonds were all caused bythe oxygen loss.

As shown in step S2 of FIG. 1, the substrate having the amorphousinsulating film formed with Zr_(0.86)Si_(0.14)O_(1.75) was placed in aheat treatment chamber, and was subjected to heat treatment. The heattreatment was performed at 800° C., and the heat treatment time was 30seconds. The atmosphere gas for the heat treatment was a mixed gas ofnitrogen and oxygen, and the mixed gas was a nitrogen-based gas,containing only 1 ppm of oxygen. The pressure in the heat treatment wasatmospheric pressure. The oxygen defect in the amorphous insulating filmformed with Zr_(0.86)Si_(0.14)O_(1.75) was compensated for in the aboveheat treatment, and the amorphous insulating film formed withZr_(0.86)Si_(0.14)O_(1.75) was transformed into an insulating filmformed with Zr_(0.86)Si_(0.14)O₂. The fact that there was no oxygen lossin the sample after the heat treatment was proved by the phenomenon thatthere were no peaks of Zr-Zr or Zr-Si bonds in the XPS measurement.

Next, X-ray diffraction measurement was carried out for the insulatingfilm formed with Zr_(0.86)Si_(0.14)O₂. The X-ray diffraction profileobtained as a result of the measurement is shown in FIG. 2. The X-raydiffraction profile shown in FIG. 2 is similar to the X-ray diffractionprofile of tetragonal zirconia calculated and shown in FIG. 3.Therefore, the insulating film formed with Zr_(0.86)Si_(0.14)O₂ producedby the method of this embodiment can be considered to be tetragonalzirconia. However, when the lattice constant of the insulating filmformed with Zr_(0.86)Si_(0.14)O₂ produced by the method of thisembodiment was measured through X-ray diffraction and was compared withthe lattice constant (a=b=0.3640 nm, c=0.5270 nm) of tetragonal zirconiadisclosed in “Acta Cryst. 15, 1187, 62”, the lattice constant of theinsulating film formed with Zr_(0.86)Si_(0.14)O₂ produced by the methodof this embodiment was approximately 1% lower (a=b=0.3605±0.0003 nm,c=0.5206±0.0006 nm). FIG. 3 shows the X-ray diffraction peak intensitiescalculated with respect to a variety of zirconia crystalline structures.

The reason that an insulating film having a tetragonal zirconiacrystalline structure that has been difficult to produce can be formedby the method of this embodiment is considered to be the existence ofstress applied onto the insulating film. More specifically, by themethod of this embodiment, an amorphous insulating film that had acomposition of Zr_(0.86)Si_(0.14)O_(1.75) with a smaller amount ofoxygen than the oxygen stoichiometry was first formed. Annealing wasthen performed to compensate for the oxygen defect. As a result, thevolume of the insulating film increased. However, since the insulatingfilm was attached to the substrate, the insulating film could not expandin the in-plane direction. Compressive stress was then applied onto theinsulating film, resulting in an approximately 1% decrease of thelattice constant of the crystals of the insulating film.

FIG. 4 is a temperature-pressure phase diagram about zirconia (see J. M.Leger, P. E. Tomaszewski, A. Atouf, and A. S. Pereira, Phys. Rev. B47,14075 (1993)). As is clear from FIG. 4, as the pressure becomes higher,the temperature at which the tetragonal crystals in zirconia can stablyexist in a crystalline state becomes lower. Accordingly, since therequirements for obtaining stable tetragonal crystals at roomtemperature were satisfied, the production of tetragonal crystals by themanufacturing method of this embodiment is considered to be a success.

Here, the insulating film disclosed in Reference 3 is again described.The insulating film disclosed in Reference 3 has a permittivityincreased by adding silicon to hafnia. The molar polarizability of theatoms in the insulating film disclosed in Reference 3 is in the range of0.00669 nm³ to 0.00673 nm³, and does not change substantially. In thatstructure, the permittivity is increased by reducing the molecularvolume (or the molar volume) by approximately 9%. According to acalculation made by the inventor, to achieve such a small molecularvolume, the stress exered by distortions in the insulating film must beas large as 9 GPa. FIG. 13 shows the results of examinations that wereconducted to check changes in lattice constant by applying stress ontohafnia (see Osamu Ohtaka, Hiroshi Fukui, Taichi Kunisada, TomoyukiFujisawa, Kenichi Funakoshi, Wataru Utsumi, Tetsuo Irifune, Koji Kuroda,and Takumi Kikegawa, J. Am. Ceram. Soc., 84[6] 1369-73 (2001)). In FIG.13, the abscissa axis indicates the stress to be applied, and theordinate axis indicates the rate of the volume V of each unit lattice ofhafnia crystals at the applied pressure to the volume V₀ of each unitlattice of hafnia crystals at atmospheric pressure. As can be seen fromFIG. 13, the hafnia that is in a thermal equilibrium state atatmospheric pressure has phase transition to an orthorhombic phase I ata high pressure, and has further phase transition to an orthorhombicphase II at a higher pressure. Those crystalline structures aredifferent from tetragonal crystalline structures, but FIG. 13 shows thata stress as large as 10 GPa needs to be applied so as to reduce themolecular volume by 9% in a monoclinic crystalline structure. In otherwords, in a hafnia film having a 9% decrease in molecular volume, astress as large as 10 GPa is exerted. It is known that even sapphire,which is the second hardest naturally-produced ore, only next todiamond, cannot endure such a large stress with crystals of macroscopicsize. In a more precise estimate, the stress in the film is not smallerthan 8 GPa. Therefore, if the insulating film disclosed in Reference 3is used as a gate insulating film in an actual LSI, the mobility mightbe reduced due to the stress applied onto the channel region in directcontact with the gate insulating film, lattice relaxation caused in thegate insulating film might return the relative permittivity to theoriginal value, or the gate insulating film might break itself becauseof the stress.

On the other hand, the stress applied onto the insulating film of thisembodiment is 1 GPa or smaller, which is much smaller than the stressapplied onto the insulating film disclosed in Reference 3. Accordingly,the device characteristics do not deteriorate.

Furthermore, Si, which is very often used in semiconductor processes asan element to be added to zirconia, is used in this embodiment.Accordingly, the production costs become as low as possible.

Also, as described later, the insulating film produced in thisembodiment has a very high permittivity, with the relative permittivitybeing 20 to 26, which is higher than the relative permittivity ofzirconia.

The composition of the above sample after the heat treatment wasdetermined by a direct measurement method in accordance with RBS, toobtain the composition values of Zr_(0.81)Si_(0.19)O₂. As long as themeasurement carried out by us is concerned, the molar ratio of[Si]/([Zr]+[Si]) determined by a direct measurement method in accordancewith RBS is considered to be more reliable. On the other hand, in thesemi-quantitative measurement by XPS, it is difficult to achieve highreliability, as there is surface contamination or the like due to theexposure of the sample in the atmosphere. However, the amount of oxygenloss is more accurate in the measurement by the XPS, since the oxygenpeak intensity is very low by RBS. Accordingly, it is assumed that acomposition of Zr_(0.81)Si_(0.19)O_(1.75) is obtained by determining themolar ratio of [Si]/([Zr]+[Si]) by RBS and determining the amount ofoxygen loss by XPS in the sample in an as-depo state before the heattreatment.

Second Embodiment

Next, a method for manufacturing a semiconductor device in accordancewith a second embodiment of the present invention is described.

First, as shown in step S1 of FIG. 1, an amorphous insulating film thathad a composition of Zr_(0.81)Si_(0.19)O_(1.80) in the semi-quantitativemeasurement by XPS with a smaller amount of oxygen than the oxygenstoichiometry was formed on a single-crystal silicon substrate that hada natural oxide film removed with a diluted hydrofluoric acid. Theamorphous insulating film was formed by a sputtering technique, and thefilm formation was carried out in a mixed atmosphere of argon andoxygen, with Zr and Si being the targets.

As shown in step S2 of FIG. 1, the substrate having the amorphousinsulating film formed with Zr_(0.81)Si_(0.19)O_(1.80) was placed in aheat treatment chamber, and was subjected to heat treatment. The heattreatment was performed at 800° C., and the heat treatment time was 8minutes. The atmosphere gas for the heat treatment was a mixed gas ofargon and oxygen, and the mixed gas was an argon-based gas, containingonly 10 ppm of oxygen. The pressure in the heat treatment wasatmospheric pressure. The oxygen defect in the amorphous insulating filmformed with Zr_(0.81)Si_(0.19)O_(1.80) was compensated for in the aboveheat treatment, and the amorphous insulating film formed withZr_(0.81)Si_(0.19)O_(1.80) was transformed into an insulating filmformed with Zr_(0.81)Si_(0.19)O₂.

Next, X-ray diffraction measurement was carried out for the insulatingfilm formed with Zr_(0.81)Si_(0.19)O₂. The X-ray diffraction profileobtained as a result of the measurement is shown in FIG. 5. The X-raydiffraction profile shown in FIG. 5 is similar to the X-ray diffractionprofile of tetragonal zirconia calculated and shown in FIG. 3.Therefore, the insulating film formed with Zr_(0.81)Si_(0.19)O₂ producedby the method of this embodiment can be considered to be tetragonalzirconia. However, when the lattice constant of the insulating filmformed with Zr_(0.81)Si_(0.19)O₂ produced by the method of thisembodiment was measured through X-ray diffraction and was compared withthe lattice constant (a=b=0.3640 nm, c=0.5270 nm) of tetragonal zirconiadisclosed in “Acta Cryst. 15, 1187, 62”, the lattice constant of theinsulating film formed with Zr_(0.81)Si_(0.19)O₂ produced by the methodof this embodiment was approximately 1% lower (a=b=0.3595±0.0005 nm,c=0.5190±0.0007 nm). As in the first embodiment, this is because thatcompressive stress was applied onto the insulating film produced by themethod of this embodiment, resulting in an approximately 1% decrease ofthe lattice constant of the crystals of the insulating film.

Thus, as in the first embodiment, a semiconductor device that has ahighest possible permittivity and do not degrade the devicecharacteristics can also be produced at low production costs in thisembodiment.

Here, the X-ray diffraction profile shown in FIG. 5 is described ingreater detail. On closer inspection, there is a small peak ofmonoclinic zirconia, as indicated by reference numeral 10. The reason ofthe existence of this peak may be that the addition of Si increases to19 atomic % in terms of the [Si]/([Si]+[Zr]) ratio. However, with such asmall amount of monoclinic crystals being added, the insulating film ofthis embodiment is still highly usable as a high-k film.

The composition of this film after the heat treatment was determined bya direct measurement method in accordance with RBS, to obtain thecomposition values of Zr_(0.76)Si_(0.24)O₂. Accordingly, it can beassumed that a composition of Zr_(0.76)Si_(0.24)O_(1.80) is obtained bydetermining the molar ratio of [Si]/([Zr]+[Si]) by RBS and determiningthe amount of oxygen loss by XPS in the sample in an as-depo statebefore the heat treatment.

Third Embodiment

Next, a method for manufacturing a semiconductor device in accordancewith a third embodiment of the present invention is described.

First, as shown in step S1 of FIG. 1, an amorphous insulating film thathad a composition of Zr_(0.99)Si_(0.01)O_(1.90) in the measurement byXPS with a smaller amount of oxygen than the oxygen stoichiometry wasformed on a single-crystal silicon substrate that had a natural oxidefilm removed with a diluted hydrofluoric acid. The amorphous insulatingfilm was formed by a sputtering technique, and the film formation wascarried out in a mixed atmosphere of argon and oxygen, with Zr and Sibeing the targets.

As shown in step S2 of FIG. 1, the substrate having the amorphousinsulating film formed with Zr_(0.99)Si_(0.01)O_(1.90) was placed in aheat treatment chamber, and was subjected to heat treatment. The heattreatment was performed at 1050° C., and the heat treatment time was 2minutes. The atmosphere gas for the heat treatment was a pure oxygengas. The pressure in the heat treatment was atmospheric pressure.Through this heat treatment, the amorphous insulating film formed withZr_(0.99)Si_(0.01)O_(1.90) was transformed into an insulating filmformed with Zr_(0.99)Si_(0.01)O₂.

X-ray diffraction measurement was carried out for the insulating filmformed with Zr_(0.99)Si_(0.01)O₂ by the manufacturing method of thisembodiment. The X-ray diffraction profile obtained as a result of themeasurement was similar to the X-ray diffraction profile of tetragonalzirconia. Therefore, the insulating film formed withZr_(0.99)Si_(0.01)O₂ produced by the method of this embodiment can beconsidered to be tetragonal zirconia.

Thus, as in the first embodiment, a semiconductor device that has ahighest possible permittivity and do not degrade the devicecharacteristics can also be produced at low production costs in thisembodiment.

As can be seen from the above embodiments, tetragonal crystals areobtained, with the heat treatment time being in the range of 30 secondsto 8 minutes, the heat treatment temperature being in the range of 800°C. to 1050° C., and the oxygen concentration in the atmosphere gas beingin the range of 1 ppm to 100%. Also, tetragonal crystals are obtained,with the atmosphere gas pressure being varied from 10⁻² Pa to 10⁵ Pa(atmospheric pressure).

As a comparative example, an insulating film having a composition ofZr_(1−x)Si_(x)O₂ without an oxygen defect was formed. In this insulatingfilm, only monoclinic or cubic crystals appeared. After the insulatingfilm having a composition of Zr_(1−x)Si_(x)O₂ as a comparative examplewas subjected to heat treatment, the monoclinic-cubic ratio was easilychanged.

By any of the manufacturing methods of the first through thirdembodiments, on the other hand, tetragonal crystals can be maintainedwith a very wide range of heat treatment conditions. As described above,it was found that there was a wide range of heat treatment conditions ina ZrSiO film having tetragonal crystals produced by any of themanufacturing methods of the first through third embodiments, and thetetragonal crystals were maintained after any type of heat treatment ineach of the procedures for manufacturing a real semiconductor device.This means that the problem with the material disclosed in Reference 3,which cannot be applied to an actual LSI process, is completely solved,and each of the embodiments is beneficial in practical use.

In each of the first through third embodiments, an amorphous insulatingfilm that had a composition of Zr_(x)Si_(1−x)O_(2−y) (0.81≦x≦0.99,0.10≦y≦0.25) in the measurement by XPS with an oxygen defect was formed.However, exactly the same tetragonal crystals as above can be obtainedby using Hf, instead of Zr, and forming an amorphous insulating filmthat has a composition of Hf_(x)Si_(1−x)O_(2−y) (0.81≦x≦0.99,0.10≦y≦0.25) in the measurement by XPS with an oxygen defect.

This is because Zr and Hf have chemical properties similar to eachother. Even with the technology as of year 2006, there is 1% of Hfcontained in generally available Zr. Although it is possible to separatethe Hf from the Zr, doing so (to emphasize the small difference betweenthe two materials) is very costly. Like in Zr, there is 1% of Zrcontained in Hf. As is apparent from those facts, the two materials havealmost no differences. In a case where a Zr oxide is compared with a Hfoxide, for example, a similar phase diagram can be formed for the Hfoxide, as shown in FIG. 6 (see O. Ohtaka, H. Fukui, T. Kunisada, T.Fujisawa, K. Funakoshi, W. Utsumi, T. Irifune, K. Kuroda, and T.Kikegawa, 3. Am. Ceram. Soc., 84[6] 1369-73 (2001)). Accordingly, it canbe easily assumed that the tetragonal crystals in a Hf oxide can bestabilized by exactly the same mechanism as the mechanism that canstabilize the tetragonal crystals in a Zr oxide.

The composition of this film after the heat treatment was determined bya direct measurement method in accordance with RBS, to obtain thecomposition values of Zr_(0.985)Si_(0.02)O₂. Accordingly, it is assumedthat a composition of Zr_(0.985)Si_(0.0224)O_(1.90) is obtained bydetermining the molar ratio of [Si]/([Zr]+[Si]) by RBS and determiningthe amount of oxygen loss by XPS in the sample in an as-depo statebefore the heat treatment. Also, it is assumed that a composition ofHf_(x)Si_(1−x)O_(2−y) (0.76≦x≦0.985, 0.10≦y≦0.25) is obtained bydetermining the molar ratio of [Si]/([Hf]+[Si]) by a direct measurementmethod in accordance with RBS and determining the amount of oxygen lossby XPS in the above HfSiO film.

Fourth Embodiment

Next, a method for manufacturing a semiconductor device in accordancewith a fourth embodiment of the present invention is described.

First, as shown in step S1 of FIG. 1, a Zr_(x)Si_(1−x)O_(2−y) was formedon a silicon substrate that had an interface oxide layer removed throughdiluted hydrofluoric acid treatment. In XPS measurement, the formed filmis an insulating film having an oxygen defect, with (x, y) being (1.00,0.046), (0.99, 0.056), (0.98, 0.053), (0.94, 0.053), (0.90, 0.043),(0.86, 0.047), (0.86, 0.049), (0.86, 0.057), (0.86, 0.059), (0.86,0.061), (0.86, 0.062), (0.86, 0.116), or (0.81, 0.083), or an insulatingfilm without an oxygen defect, with x being 1.00, 0.99, 0.98, 0.90,0.87, or 0.70.

When the molar ratio of [Si]/([Zr]+[Si]) is measured by RBS while theoxygen defect is measured by XPS, the above film is an insulating filmhaving an oxygen defect, with (x, y) being (1.00, 0.046), (0.985,0.056), (0.97, 0.053), (0.92, 0.053), (0.86, 0.043), (0.81, 0.047),(0.81, 0.049), (0.81, 0.057), (0.81, 0.059), (0.81, 0.061), (0.81,0.062), (0.81, 0.116), or (0.76, 0.083), or an insulating film withoutan oxygen defect, with x being 1.00, 0.985, 0.97, 0.86, 0.81, or 0.66.

In the case of an insulating film having an oxygen defect, XPSmeasurement was carried out to confirm that a Zr-Si bond due to theoxygen defect was observed, as shown in FIG. 7.

In the case of an insulating film without an oxygen defect, only anamorphous film or monoclinic crystals or cubic crystals were formed evenby a deposition method or through annealing.

Next, as shown in step S2 of FIG. 1, annealing was performed on aninsulating film having an oxygen defect. In this case, substantiallyperfect tetragonal crystals were formed under any of the followingannealing conditions: (750° C., in a nitrogen gas, 30 seconds), (750°C., in a nitrogen gas, 60 seconds), (750° C., in a nitrogen gas, 2minutes), (750° C., in a nitrogen gas, 4 minutes), (750° C., in anitrogen gas, 8 minutes), (750° C., 3% of oxygen and 97% of nitrogen, 30seconds), (750° C., 3% of oxygen and 97% of nitrogen, 60 seconds), (750°C., 3% of oxygen and 97% of nitrogen, 2 minutes), (750° C., 3% of oxygenand 97% of nitrogen, 4 minutes), (750° C., 3% of oxygen and 97% ofnitrogen, 8 minutes), (750° C., in an oxygen gas, 30 seconds), (750° C.,in an oxygen gas, 1 minute), (750° C., in an oxygen gas, 2 minutes),(750° C., in an oxygen gas, 4 minutes), (750° C., in an oxygen gas, 8minutes), (1000° C., in a nitrogen gas, 30 seconds), (1000° C., in anitrogen gas, 60 seconds), (1000° C., in a nitrogen gas, 2 minutes),(1000° C., in a nitrogen gas, 4 minutes), (1000° C., in a nitrogen gas,8 minutes), (1000° C., 3% of oxygen and 97% of nitrogen, 30 seconds),(1000° C., 3% of oxygen and 97% of nitrogen, 60 seconds), (1000° C., 3%of oxygen and 97% of nitrogen, 2 minutes), (1000° C., 3% of oxygen and97% of nitrogen, 4 minutes), (1000° C., 3% of oxygen and 97% ofnitrogen, 8 minutes), (1000° C., in an oxygen gas, 30 seconds), (1000°C., in an oxygen gas, 1 minute), (1000° C., in an oxygen gas, 2minutes), (1000° C., in an oxygen gas, 4 minutes), and (1000° C., in anoxygen gas, 8 minutes).

There are two purposes of the annealing process in this case: the firstone is to compensate for the oxygen defect; and the second one is tosecure the stability of the structure against the heat treatment or tomake sure that there is no relaxation or self-destruction in thestructure. The results of this embodiment serve both purposes.Particularly, the second purpose is well served, as the tetragonalcrystals can be maintained as they are even under the above various heattreatment conditions. Accordingly, this embodiment should be very usefulwhen applied to an actual LSI process that involves various heattreatment procedures.

When the annealing conditions were more closely examined, it wasconfirmed that, with the oxygen concentration in the atmosphere being 1%or higher, minute silicide crystals unsuitable for a gate insulatingfilm could be completely prevented from growing at the interface withthe silicon substrate. Accordingly, an oxygen concentration of 1% orhigher in the atmosphere is a more preferred annealing condition.

As insulating films each having a composition of (0.86, 0.049) in theXPS measurement and a composition of (0.81, 0.049) in the RBSmeasurement, samples of 110 nm, 50 nm, 20 nm, 10 nm, and 5 nm in filmthickness were prepared, and the oxygen defect was compensated for byperforming annealing under the following conditions: (750° C., in anoxygen gas, 30 seconds), (800° C., in a nitrogen gas, 30 seconds), and(1000° C., in an oxygen gas, 30 seconds). An in-plane X-ray diffractiontest was conducted for the insulating films of 10 nm and 5 nm inthickness, and the crystalline structures were examined to findperfectly tetragonal, fluorite-type crystalline structures, as shown inFIG. 8. We confirmed that every peak position coincided with tetragonalone. As for the insulating films of 10 nm in thickness, the in-planeX-ray diffraction test was conducted only for the samples annealed underthe condition of (800° C., in a nitrogen gas, 30 seconds), and theresult of this test is shown in FIG. 8.

There were conventional tetragonal zirconia films that had silicon addedthereto. However, many of them are power samples or sintered samples, orare thick films of approximately 1 μm in thickness formed by the sol-gelmethod or the like.

Accordingly, thin films of 5 nm and 10 nm in thickness that can be usedas gate insulating films, interpoly insulating films, or blockinginsulating films as disclosed in this embodiment were unheard of. Themolecular volume V_(m) of those films calculated on the basis of X-raydiffraction data (lattice constants) was in the range of 0.03353nm³≦V_(m)≦0.03424 nm³ per Zr_(x)Si_(1−x)O₂. The molecular volumereduction rate was 3%. Accordingly, it is reaffirmed that those films ofthis embodiment have in-film stress that can endure a LSI process,unlike the insulating film disclosed in Reference 3, which has themolecular volume reduction rate of 9%.

The reason that the in-film stress by the manufacturing method of thisembodiment can endure a LSI process is considered to be the differencein manufacturing method. By the manufacturing method of this embodiment,after an amorphous ZrSiO film is formed, tetragonal crystals areobtained through an annealing process that is a thermalquasi-equilibrium process. As a result of the semi thermal equilibriumprocess, the in-film stress is reduced.

By the method disclosed in Reference 3, on the other hand, a HfSiO filmis formed by performing sputtering on a HfO₂ target and a SiO₂ target.It is a well-known fact that a sputtering process as a thermalnonequilibrium process generates a large in-film stress.

In this embodiment, the relative permittivity of each of the insulatingfilms having the oxygen defect compensated for after the annealing wasmeasured. The compositions in the XPS measurement before the annealingwere (1.00, 0.046), (0.99, 0.056), (0.98, 0.053), (0.94, 0.053), (0.90,0.043), and (0.86, 0.047). The compositions in the XPS measurement afterthe annealing were (1.00, 0.00), (0.99, 0.00), (0.98, 0.00), (0.94,0.00), (0.90, 0.00), and (0.86, 0.00), with the oxygen defect havingbeen compensated for.

With the molar ratio of [Si]/([Zr]+[Si]) being measured by RBS and theoxygen defect amount being measured by XPS, the composition of thesamples before the annealing are considered to be (1.00, 0.046), (0.985,0.056), (0.97, 0.053), (0.92, 0.053), (0.86, 0.043), and (0.81, 0.047).The compositions after the annealing were (1.00, 0.00), (0.985, 0.00),(0.97, 0.00), (0.92, 0.00), (0.86, 0.00), and (0.81, 0.00). In theestimates of the amounts of oxygen defect by XPS, the oxygen defect wascompensated for.

For measurement of electric properties, a gold electrode was formed oneach film after the annealing, so as to make sure that the electroderesistance was sufficiently low.

FIG. 9 shows the results of the relative permittivity measurement. InFIG. 9, the abscissa axis indicates the value of ([Si]/([Si]+[Zr]))×100(atomic %) measured by XPS, and the ordinate axis indicates the relativepermittivity of each insulating film or the ratio of the permittivity εof the insulating film to the permittivity ε₀ of vacuum. As can be seenfrom FIG. 9, the relative permittivity was 20 to 26, with the value of xmeasured by XPS in a Zr_(x)Si_(1−x)O₂ film being in the range of 0.86 to0.94 (with the value of z in a Zr_(1−z)Si_(z)O₂ film being in the rangeof 0.06 to 0.14). Since the relative permittivity of a conventional ZrO₂film was approximately 17, increases in permittivity were confirmed.

In this embodiment, the molar polarizability a of the atoms ininsulating films each having the oxygen defect compensated for after theannealing was calculated with the use of the above measured relativepermittivity and lattice constant and the Clausius-Mosotti equation, tofind increases to 0.00679 nm³<α≦0.00735 nm³. This result is apparentlydifferent from the result disclosed in Reference 3, which is that themolar polarizability of atoms hardly varies even though the permittivityincreases as the crystalline system is changed to a tetragonalcrystalline system. Therefore, this embodiment should be considered tohave successfully produced a different substance from the substancedisclosed in Reference 3.

When the crystalline structure of each of the insulating films ofZr_(x)Si_(1−x)O₂ formed in this embodiment was more closely examined, itwas found that not only tetragonal crystals but also an orientation thatallows the effective use of the crystal axis with the higherpermittivity was obtained. In a gate electrode of a transistor, aninterelectrode insulating film of a flash memory, a blocking insulatingfilm of a flash memory, or a capacitor insulating film, it is thepermittivity in the film thickness direction that affects a real device.Therefore, where the crystal axis with the higher permittivity isoriented in the film thickness direction, higher permittivity can beachieved.

As an examination result, it was confirmed that, in the sample having avalue of 0.90 as the composition ratio x of Zr measured by XPS, the[110] orientation as the crystal axis with the higher permittivity inthe tetragonal crystals, which is the a′ axis direction, wassubstantially in parallel with the film thickness direction, and thepermittivity of the sample was actually the highest (see FIG. 9). Here,the composition ratio x of Zr as a value measured by RBS was 0.86. Withcells twice as many as the unit cells being taken into account, the[110] orientation in the unit cells is set as the a′ axis of the cellstwice as many as the unit cells. It should be noted that the a′ axis isreferred to simply as the “a axis” in some documents.

Meanwhile, it was confirmed that, in the sample having a value of 0.94as the composition ratio x of Zr measured by XPS, the c axis as thecrystal axis with the lower permittivity in the tetragonal crystals wassubstantially in parallel with the film thickness direction, and thepermittivity of the sample was actually the lowest in the tetragonalcrystals. Here, the composition ratio x of Zr as a value measured by RBSwas 0.92. In each of the insulating films of Zr_(x)Si_(1−x)O₂ formed inthis embodiment, the c′ axis of the cells twice as many as the unitcells is exactly the same as the c axis of the unit cells. Furthermore,the difference in length between the a′ axis and the c′ axis isapproximately 3%, for example, and the length of the a′ axis is alwayssmaller than the length of the c′ axis.

Further, the sample having a value of 0.86 as the composition ratio x ofZr measured by XPS had a value of 0.81 as the composition ratio xmeasured by RBS. However, it was confirmed that an orientation was notobserved though tetragonal crystals were obtained. Actually, thepermittivity of this sample was lower than the permittivity of thesample having a value of 0.90 as the composition ratio x of Zr measuredby XPS or the sample having a value of 0.86 as the composition ratio xmeasured by RBS, but was higher than the permittivity of the samplehaving a value of 0.94 as the composition ratio x of Zr measured by XPSor the sample having a value of 0.92 as the composition ratio x measuredby RBS (see FIG. 9). The estimates made through the first principlecalculations were different from the experimental values quantitatively,but were proved to be qualitatively correct through experiments.

FIG. 14 shows the X-ray diffraction profiles of insulating films ofZr_(x)Si_(1−x)O₂, with the value x of Zr in the XPS measurement being0.86, 0.90, 0.94, 0.98, and 1.00, or with the value of x of Zr in theRBS measurement being 0.81, 0.86, 0.92, 0.97, and 1.00. Since the peakintensities are logarithmically plotted in FIG. 14, attention isrequired when the peak intensities are compared with one another. Inthis specification, an index is put to the diffraction peaks in theX-ray diffraction profiles shown in FIG. 14, with the use of cells twiceas many as the unit cells. The diffraction index used here is a′, b′,and c, instead of a, b, and c crystalline system. In FIG. 14, “111”,“002”, “200”, “112”, “202”, “220”, “113”, “311”, and “222” represent thediffraction index a′, b′, and c crystalline system.

In the sample having a value of 0.86 as the composition ratio x of Zrmeasured by XPS or the sample having a value of 0.81 as the compositionratio x measured by RBS, the diffraction peak of 200 in diffractionindex that is the sum of the diffraction peak 200 in the a′ axis and thediffraction peak 020 in the b′ axis, which are equivalent to each other,is larger than the peak of 002 in diffraction index in the c-axis as asingle peak. Likewise, the peak of 300 in diffraction index is the sumof the equivalent diffraction index 131 and the diffraction peak 300,but is larger than the peak of 113 in diffraction index as a singlepeak. Since those peak intensities are affected by minute atomdisplacements, the intensity ratio is not always 2:1. However, as longas the sample has no orientations, the intensity ratio does not changeas much as to reverse the relationship in intensity. In practice, theintensity ratio is close to 2:1. Accordingly, the sample having a valueof 0.86 as the composition ratio x of Zr measured by XPS or the samplehaving a value of 0.81 as the composition ratio x measured by RBS doesnot have an orientation. Also, in the sample having a value 0.90 as thecomposition ratio x of Zr, the diffraction peak in the a′ axisdirection, such as the diffraction index 200, is very intense, and thea′ axis lies in the film thickness direction. In the sample having avalue 0.94 as the composition ratios x of Zr measured by XPS or thesample having a value of 0.92 as the composition ratio x measured byRBS, the peaks having components of the c-axis direction, such as thediffraction indexes 200, 112, 202, and 113, are relatively intense, andthere is an orientation in the c axis direction.

As in the above described case, it can be easily assumed that thetetragonal crystals in a Hf oxide can be stabilized by exactly the samemechanism as the mechanism that can stabilize the tetragonal crystals ina Zr oxide.

Although the heat treatment temperature is in the range of 750° to 1000°C. in this embodiment, it is also possible to carry out the heattreatment at temperatures in the range of 750° C. to 1100° C.

Fifth Embodiment

Next, a semiconductor device in accordance with a fifth embodiment ofthe present invention is described. The semiconductor device of thisembodiment is the same as the semiconductor device produced by any ofthe manufacturing method of the first through fourth embodiments, exceptthat the insulating film is replaced with an insulating film formed with(Zr_(1−z)Hf_(z))_(x)Si_(1−x)O_(2−y) (in the XPS measurement: 0≦z≦1,0.86≦x≦0.99; in the RBS measurement: 0≦z≦1, 0.81≦x≦0.985, 0.04≦y≦0.25).

It is a known fact that ZrO₂ and HfO₂ can form mixed crystals at anyratio. FIG. 10 shows a phase diagram of ZrO₂ and HfO₂ at all the ratios(see Ruh, H. J. Garrett, R. F. Domagla, and N. M. Tallan, J. Amer.Ceram. Soc., 51, [1]27 (1968)). The phase diagram of FIG. 10 is a verysimple diagram, and the regions of the respective phases of tetragonalcrystals, cubic crystals, and monoclinic crystals exist for all thecompositions ranging from ZrO₂ to (Hf_(z)Zr_(1−z))O₂ to HfO₂. Theboundaries of the respective phases do not cross one another. It can beconsidered that such a phase diagram is obtained, because Zr and Hf havechemical properties very similar to each other.

Accordingly, as in the first through fourth embodiments, an amorphousinsulating film formed with (Zr_(1−z)Hf_(z))_(x)Si_(1−x)O_(2−y) (in theXPS measurement: 0≦z≦1, 0.86≦x≦0.99; with the molar ratio of[Si]/([Zr]+[Hf]+[Si]) and the molar ratio of [Hf]/([Zr]+[Hf]) beingmeasured by RBS, with the amount of oxygen defect being measured by XPS,0≦z≦1, 0.81≦x≦0.985, and 0≦z≦1, 0.86≦x≦0.99, 0.04≦y≦0.25) can betransformed into (Hf_(z)Zr_(1−z))_(x)Si_(1−x)O₂ (0≦z≦1, in the XPSmeasurement: 0.86≦x≦0.99, in the RBS measurement: 0.81≦x≦0.985) byannealing, so as to compensate for the oxygen defect and obtaintetragonal crystals. Since an increase in permittivity by virtue of thetetragonal crystals is achieved with ZrO₂ and HfO₂, it is also achievedwith (Zr_(1−z)Hf_(z))O₂, which is an intermediate state between the twooxides. The same applied to cases where tetragonal crystals are obtainedby adding a very small amount (x in this case) of Si.

Thus, this embodiment can achieve the same effects as those of the firstthrough fourth embodiments, with (Zr_(1−z)Hf_(z))_(x)Si_(1−x)O₂ beingused as an insulating film.

As described so far, in the first through fifth embodiments of thepresent invention, insulating films with such high permittivity thatcannot be formed with conventional high-k insulating films of zirconiaor hafnia can be produced by adding Si, which is highly compatible withconventional semiconductor processes. The high-k insulating films of theabove described embodiments are zirconia-based films, hafnia-basedfilms, or films formed with a mixed material of zirconia and hafnia.

In each of the first through fifth embodiments of the present invention,the in-film stress is restricted to 1 GPa or less, and the molecularvolume hardly affects the mechanism of increasing the permittivity.Accordingly, there are fewer distortions in the films, and the problemof relaxation and the problem of self-destruction due to stress can besolved.

Sixth Embodiment

Next, a semiconductor device in accordance with a sixth embodiment ofthe present invention is described.

The semiconductor device of this embodiment has an insulating film withcompensated oxygen that is disclosed in any one of the first throughfifth embodiments. In this embodiment, the insulating film is used as agate insulating film of a MOS, particularly, as a gate insulating of aCMOS, an interelectrode insulating film of a flash memory, or a blockinginsulating film of a flash memory.

FIG. 11 is a cross-sectional view of a semiconductor device having aCMOSFET as a first specific example of this embodiment. Thissemiconductor device as the first specific example includes an n-channelMOSFET 32 and a p-channel MOSFET 33 that are formed on a semiconductorsubstrate 20. The n-channel MOSFET 32 is provided in a p-well region 22formed in the semiconductor substrate 20. The n-channel MOSFET 32includes a gate insulating film 24 formed on the p-well region 22, agate electrode 25 formed on the gate insulating film 24, source anddrain regions 28 formed with n⁺-impurity regions located at portions ofthe p-well region 22 on either side of the gate electrode 25, and gatesidewalls 27 formed with an insulating material provided on the sidefaces of the gate electrode 25.

The p-channel MOSFET 33 is provided in an n-well region 23 formed in thesemiconductor substrate 20. The p-channel MOSFET 33 includes a gateinsulating film 24 formed on the n-well region 23, a gate electrode 26formed on the gate insulating film 24, source and drain regions 29formed with p⁺-impurity regions located at the portions of the n-wellregion 23 on either side of the gate electrode 26, and gate sidewalls 27formed with an insulating material provided on the side faces of thegate electrode 26. The p-well region 22 and the n-well region 23 areisolated from each other by a device isolating region 21. The source anddrain regions 28 and 29 have extension regions that extend below thegate insulating films 24.

In the semiconductor device as the first specific example, the gateinsulating film 24 of each of the n-channel MOSFET 22 and the p-channelMOSFET 23 is an insulating film with compensated oxygen that isdisclosed in any one of the first through fifth embodiments.

Referring now to FIG. 12, a semiconductor device as a second specificexample of this embodiment is described. This semiconductor device asthe second specific example is a flash memory, and a cross-sectionalview of a memory cell 50 is shown in FIG. 12. This memory cell 50includes a tunnel insulating film 42 formed on a semiconductor substrate40, a gate electrode 44 formed on the tunnel insulating film 42, sourceand drain regions 49 formed at the portions of the semiconductorsubstrate 40 on either side of the gate electrode 44, and gate sidewalls48 formed with an insulating material provided on the side faces of thegate electrode 44. The gate electrode 44 includes a floating gate 45formed on the tunnel insulating film 42, an interelectrode insulatingfilm 46 formed on the floating gate 45, and a control gate 47 formed onthe interelectrode insulating film 46. In this specific example, theinterelectrode insulating film 46 is an insulating film with compensatedoxygen that is disclosed in any one of the first through fifthembodiments.

In the second specific example, a floating gate type flash memory hasbeen described. The insulating film with compensated oxygen that isdisclosed in any one of the first through fifth embodiments isapplicable to a MONOS (Metal-Oxide-Nitride-Oxide-Silicon) type flashmemory. As shown in FIG. 15, the MONOS type flash memory 50A includes amemory cell that contains a tunnel insulating film 42 formed on asemiconductor substrate 40, a gate electrode 44A formed on the tunnelinsulating film 42, source and drain regions 49 formed at the portionsof the semiconductor substrate 40 on either side of the gate electrode44A, and gate sidewalls 48 formed with an insulating material providedon the side faces of the gate electrode 44A. The gate electrode 44Aincludes a charge storing layer 51 formed on the tunnel insulating film42, a blocking insulating film 46A formed on the charge storing layer51, and a control gate 47 formed on the blocking insulating film 46A.The blocking insulating film 46A is an insulating film with compensatedoxygen that is disclosed in any one of the first through fifthembodiments.

When the insulating film with compensated oxygen that is disclosed inany one of the first through fifth embodiments is used as theinterelectrode insulating film or the blocking insulating film, theinsulating film can be a single layer or a stacked layer.

Since the gate insulating films 24 of the first specific example, theinterelectrode insulating film 46 of the second specific example and theblocking insulating film 46A of MONOS type flash memory of thisembodiment are insulating films with compensated oxygen that aredisclosed in any of the first through fifth embodiments, the in-filmstress is restricted to 1 GPa or less, and the molecular volume hardlyaffects the mechanism of increasing the permittivity. Accordingly, thereare fewer distortions in the films, and the problem of relaxation andthe problem of self-destruction due to stress can be solved. Thus,device characteristics degradation can be prevented.

For reference, the results of XPS measurement and RBS measurement of Sicompositions in the respective insulating films of the first throughsixth embodiments of the present invention are shown in the table below.

TABLE Si Amount XPS RBS composition composition  0%   0%  1% 1.5%  2%  3%  6%   8% 10%  14% 14%  19% 19%  24%

Additional advantages and modifications will readily occur to thoseskilled in the art. Therefore, the invention in its broader aspects isnot limited to the specific details and representative embodiments shownand described herein. Accordingly, various modifications may be madewithout departing from the spirit or scope of the general inventiveconcepts as defined by the appended claims and their equivalents.

1. A method for manufacturing a semiconductor device, comprising: forming an amorphous film containing (Hf_(z)Zr_(1−z))_(x)Si_(1−x)O_(2−y) (0.81≦x≦0.99, 0.04≦y≦0.25, 0≦z≦1) on a semiconductor substrate, the ranges of composition ratios x, y, and z being values measured by XPS; and transforming the amorphous film into an insulating film containing (Hf_(z)Zr_(1−z))_(x)Si_(1−x)O₂ as tetragonal crystals, by performing annealing at 750° C. or higher on the amorphous film in an atmosphere containing oxygen.
 2. The method according to claim 1, wherein a pressure in the atmosphere in which the annealing is performed is atmospheric pressure.
 3. The method according to claim 1, wherein oxygen content in the atmosphere containing oxygen is 1 ppm or higher.
 4. The method according to claim 1, wherein oxygen content in the atmosphere containing oxygen is 1% or higher. 5-22. (canceled)
 23. The method according to claim 1, wherein molecular volume V_(m) of tetragonal crystals in the insulating film is in the range of 0.03353 nm³≦V_(m)≦0.03424 nm³, and the insulating film has a physical film thickness of 110 nm or smaller.
 24. The method according to claim 1, wherein lattice constants a, b, and c of tetragonal unit cells in the insulating film are in the ranges of 0.3590 nm≦a≦0.3608 nm, 0.3590 nm≦b≦0.3608 nm, and 0.5183 nm≦c≦0.5212 nm, respectively.
 25. The method according to claim 1, wherein the insulating film has relative permittivity ranging from 20 to 26; and molar polarizability α of atoms constituting the insulating film is in the range of 0.00679 nm³<α≦0.00735 nm³.
 26. The method according to claim 1, wherein a′ axis of the tetragonal crystals in the semiconductor film extends substantially parallel to a film thickness direction of the insulating film.
 27. The method according to claim 1, wherein the stress applied onto the insulating film is 1 GPa or smaller.
 28. The method according to claim 1, wherein the insulating film is a gate insulating film of a CMOSFET.
 29. The method according to claim 1, wherein the insulating film is an interelectrode insulating film of a floating gate type flash memory.
 30. The method according to claim 1, wherein the insulating film is a blocking insulating film of a MONOS type flash memory. 